Point source light-emitting diode

ABSTRACT

A point source light emitting-diode (LED) comprises a substrate, an epitaxy structure, a first electrode, an isolation layer, a bonding layer, a contact layer, and a connection bridge. The epitaxy structure is located on the substrate, and the substrate has a pattern including a light emitting area located on the light-emitting surface of the epitaxy structure. The first electrode is located on the substrate, and the isolation layer is located on the epitaxy structure adjacent to the first electrode. The contact layer is located on the first electrode, and the bonding layer is located on one portion of the isolation layer. The connection bridge with a width less than one half of the diameter of the light emitting area is located on the other portion of the isolation layer, thereby connecting the contact layer and the bonding layer.

RELATED APPLICATIONS

The present application is based on, and claims priority from, TaiwanApplication Serial Number 93130575, filed on Oct. 8, 2004, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

The present invention relates to a light-emitting diode (LED), and moreparticularly, to the point source LED having an improved surface featureand the manufacturing method for making the same.

BACKGROUND OF THE INVENTION

A LED is a p-n junction diode that can emit light of variouswavelengths, and has the characteristics of low power consumption, lowheat generation, long operational life, small volume, good impactresistance, fast response, and excellent stability, so that the LED hasbeen popularly used in electric appliance field as a light source.

In optoelectric applications, a LED also has been used as an importantactive component of optical fiber communications, due to its reliabilityand high beam-coupling ratio with the optical fiber. Generally, toobtain high light-coupling efficiency with optical fibers, a pointsource LED is selected as the light source of communications, because ofits lower view angel. However, a conventional LED having a bonding arealocated on the center of the light emitting area not only restricts thelight emitting that can affect the emitting shape, but also reduces thelight emitting efficiency.

To resolve this problem, a lens is provided to concentrate the lightemitted from the point source LED into a light beam. However, theaddition of lens requiring additional assembly processes and materialsis not competitive in the market.

U.S. Pat. No. 6,063,643 provides a method of concentrating the localcurrent into a LED to produce the concentrated emitting light. In thedisclosed art, a light-emitting diode is etched to form an emittingarea. Then the epitaxy structure and the electrode surrounding the lightemitting area are selectively oxidized. By the treatment, theconventional problems of light emitting restriction can be avoided, sothat, the emitted light can be focused into a light beam without anyadditional lenses. However, only the materials suitable for oxidizing,such as AlGaAs or AlAs can be used as the epitaxy structure. And thetreatment of selective oxidization conducted on the epitaxy structurecan increase the complexity and cost of the LED manufacturing processes.

Japanese Unexamined Patent Publication (Kokai) No. Heisei 2-174272discloses another LED of high brightness. In the disclosed art, byetching the epitaxy structure of the LED, a light emitting area isprovided. Consequently, a circle electrode is provided by a series ofdoping and etching processes. Through the treatment, the lightness ofthe LED can be increased and the light can be concentrated into a singlebeam. However the doping process requires high operation temperaturesthat could cause the degradation of the LED.

It is desirable; therefore, to provide a point source LED with highlightness, concentrative emitting light, and with simple manufacturingprocesses.

SUMMARY OF THE INVENTION

Therefore, one objective of the present invention is to provide a pointsource LED with high lightness, concentrative emitting light, simplemanufacturing processes and the method for making the point LED toresolve the problems of low light-coupling efficiency of theconventional LED used in optical fiber communication devices.

In an embodiment of the present invention, a point source LED isprovided. The point source LED comprises a substrate, an epitaxystructure, a first electrode, an isolation layer, a bonding layer, acontact layer, and a connection bridge, wherein the epitaxy structure islocated on the substrate having a pattern that includes a light emittingarea located on the light emitting surface of the epitaxy structure; thefirst electrode is located on the substrate; the isolation layer islocated on the epitaxy structure in adjacent to the first electrode; thecontact layer is formed on the first electrode; the bonding layer islocated on one portion of the isolation layer having a width that isless than one half of the diameter of the light emitting area located onthe other portion of the isolation layer, and making a connectionbetween the contact layer and the bonding layer.

According to another preferred embodiments of the present invention, themanufacturing method of the point source LED aforementioned is provided.First, a substrate is provided. An epitaxy structure is formed on thesubstrate. Forming a first electrode on one portion of the epitaxystructure before an isolation layer is formed on the other portion ofthe epitaxy structure adjacent to the first electrode. Then, a metallayer is formed in adjacency to the first electrode and the isolationlayer. After the metal layer is formed, a patterning process isperformed on the metal layer to define the metal layer into three partsincluding a connecting bridge, and a contact layer. A mesa etch is thenconducted onto the epitaxy structure, so that at least one portion ofthe epitaxy structure below the contact area remains so as to form alight emitting area. Then, a second electrode is formed. Consequently, aseries of downstream processes are performed to complete the pointsource LED.

The point source LED is used to concentrate the local current flowingthrough the contact layer to enhance the emitted light focusing into alight beam.

Accordingly, the LED with increased brightness and beam-coupling ratiocan be accomplished by the present invention, and the present inventioncan resolve the light emitting problems due to the bonding processeswithout adding any complex processes.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawing, wherein:

FIG. 1 a is a cross sectional diagram showing a point source LED inaccordance with the first embodiment of the present invention.

FIG. 1 b is a top view diagram showing a point source LED in accordancewith the first embodiment of the present invention.

FIG. 1 c is a cross sectional diagram showing a point source LED inaccordance with the first embodiment of the present invention.

FIG. 1 d is a top view diagram showing a contact layer, a bonding layer,and a connection bridge in accordance with the first embodiment of thepresent invention.

FIG. 1 e is a top view diagram showing a point source LED in accordancewith the first embodiment of the present invention.

FIG. 2 a to FIG. 2 h are a series of cross sectional diagrams showingthe process steps of the point source LED in accordance with the secondembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention discloses a point source LED for optical fibercommunications and the manufacturing method for making the point sourceLED. The point source LED with increased brightness and beam-couplingratio is accomplished without adding any complex processes. Therefore,the emitted light can be focused into to a predetermined shape.

According the present invention, the LED comprises a substrate, anepitaxy structure, a first electrode, and a second electrode, anisolation layer, a contact layer a connection bridge, and a bondinglayer are provided.

Referring to FIG. 1 a, FIG. 1 a is a cross sectional diagram showing apoint source LED in accordance with the first embodiment of the presentinvention. In the fist embodiment of the present invention, the epitaxystructure 102 is grown on the substrate 100, wherein the substrate 100is preferably made of n-type GaAs. The epitaxy structure 102 is made ofIII–V semiconductor materials, such as GaP, Ga_(1-x)Al_(x)As,GaAs_(1-y)P_(y), ZnS_(1-z)Se_(z), AlGaInP, AlInGaN, wherein MgZnSSe,AlGaInP, AlInGaN, MgZnSSe, and Ga_(1-x)Al_(x)As preferably. The epitaxystructure 102 includes a plurality of layers, such as a buffer layer101, an n-type cladding layer 103, an active layer 105, and a P-typecladding layer 107 stacked sequentially. In the embodiment, the materialof buffer layer 101 may be preferably such as n-type GaAs. The n-typecladding layer 103 may be made of a wide bandgap n-type AlGaInP,preferably. The active layer 105 may be preferably made of narrowbandgap AlGaInP, or AlGaInP with multi-quantum well. The material ofp-type cladding layer 107 may be preferably such as wide bandgap p-typeAlGaInP.

Referring to FIG. 1 b, FIG. 1 b is a top view diagram showing a pointsource LED in accordance with the first embodiment of the presentinvention. In the first embodiment of the present invention, the epitaxystructure 102 has a pattern that at least includes a light emitting areaL. The light emitting area L can be in various shapes including acircle, a ring, a polygon, or a cross. In the first embodiment of thepresent invention, the light emitting area L may be a circle with adiameter less than 150 μm. According to the present invention, thepattern of the epitaxy structure 102 is located in the cladding layerfor emitting light. In some embodiments of the present invention, thepattern is located in the n-type cladding layer 103. In the otherembodiments of the present invention, the pattern is located in thep-type cladding 107. In the first embodiment of the present invention,the pattern of the epitaxy structure 102 is located in the n-typecladding layer 103.

Referring to FIG. 1 c, a first electrode 104 and a second electrode 106are formed on the epitaxy structure 102, and the first electrode 104cannot directly contact the second electrode 106. In some embodiments ofthe present invention, the first electrode 104 and the second electrode106 are located on the same side of the substrate 100 (referring to FIG.1 a). In the other embodiments of the present invention, the firstelectrode 104 and the second electrode 106 are located on the oppositesides of the substrate 100 respectively (Referring to FIG. 1 c). In thefirst embodiment of the present invention, the first electrode 104 andthe second electrode 106 are located on the opposite sides of thesubstrate 100 respectively. According to the present invention, the fistelectrode 104 is a patterned layer. The patterned layer can be invarious shapes comprising a circle, a ring, a polygon, or a cross. Inthe first embodiment of the present invention, the first electrode 104may be a cross. The materials used to form the first electrode 104 orthe second electrode 106 may be the material of excellent conductivitywith the epitaxy structure 102, such as an ohmic metal or a transparentconductive material, wherein the transparent conductive material can besuch as ITO (Indium-Tin-Txide), ZnO, SnCdO, WTiN, InO, SnO or MgO. Theohmic metal can be such as Au, Ag, Al, Ni, Ti, Ge/Au alloy, or othermetal. In the first embodiment of the present invention, the firstelectrode 104 and the second electrode 106 are made of Ge/Au alloy.

Referring to FIG. 1 b, an isolation layer 108 is formed on the epitaxystructure 102 adjacent to the first electrode 104. The isolation layer108 is made of isolation materials, such as SiON, SiNx, SiO₂, AlO₂ orpolyimide, and the preferrable material is SiNx.

Referring to FIG. 1 d, FIG. 1 d is a top view diagram showing astructure including a contact layer 110, a bonding layer 112, and aconnection bridge 114 in accordance with the first embodiment of thepresent invention. The contact layer 110 is adjacent to the firstelectrode 104, and an electric contact is formed between the contactlayer 110 and the first electrode 104. According to the presentinvention, the contact layer 110 is also a patterned conductive layer.The contact layer 110 can be in various shapes, such as a circle, aring, a polygon, or a cross. In the first embodiment of the presentinvention, the contact layer 110 may be a cross in alignment with thefirst electrode 104. The bonding layer 112 as a target area forpositioning purpose in the consequent bonding process is formed inadjacency to the isolation layer 108 and the connection bridge 114. Theconnection bridge 114 formed on the isolation layer 108 is a narrowelectrically conductive passage as a connection between the bondinglayer 112 and the contact layer 110, and makes a electric contactbetween the bonding layer 112 and the contact layer 110. The preferablewidth of the connection bridge 114 is less than one half of the diameterof the light emitting area L. In the present invention, each of thecontact layer 110, the bonding layer 112 and the connection bridge 114cannot connect with the second electrode directly. The isolation layer108 is used for dividing the epitaxy structure 102 from each of thecontact layer 110, the bonding layer 112 and the connection bridge 114to prevent the forming of electric contacts between the epitaxystructure 102 and each of the contact layer 110, the bonding layer 112,and the connection bridge 114 directly. In some embodiments, the contactlayer 110, the bonding layer 112, and the connection bridge 114 may beformed simultaneously with the same materials by the same processes. Inthe other embodiments, the contact layer 110, the bonding layer 112, andthe connection bridge 114 may be formed respectively with differentmaterials by different processes. The preferable materials, such as Au,Ag, Al, Ni, Ti, Cr, Au alloy, or other metal, are used for forming eachof the contact layer 110, the bonding layer 112, and the connectionbridge 114. In the first embodiment of the present invention, thecontact layer 110, the bonding layer 112, and the connection bridge 114are formed within the same conductive layer that is made of Au alloy bythe same process. The connection bridge 114 has a width, and the widthis less than 30 μm.

In the first embodiment of the present invention, the point source LEDfurther comprises a passive layer 116 formed on each of the contactlayer 110, the bonding layer 112, the connection bridge 114, theisolation layer 108, and the epitaxy structure 102. The preferablematerial for forming the passive layer 116 is such as SiNx, SiNxOy or SiO₂.

Referring to FIG. 1 e, FIG. 1 e is a top view diagram of a point sourceLED in accordance with the first embodiment of the present invention.The outer layer of the point source LED is the passive layer 116 havinga pattern that can expose one portion of the bonding layer 112. Thebonding process can be conducted onto the exposed portion of the bondinglayer 112, named as bonding area B. An electric contact can be formedbetween an outer conductive wire (not shown) and the bonding area B.Such that, current flowing from the outer conductive wire can beconducted into the epitaxy structure 102 through the bonding area B, theconnection bridge 114, the contact layer 110, and the first electrode104 sequentially. The currenct can be concentrated in the light emittingarea L below the first electrode 104 before flowing into the activelayer 105, due to the patterns formed on the first electrode 104, thecontact layer 106, and the connection bridge 114. Light emitted from theactive layer 105 can go through the light emitting area L, the firstelectrode 104, and the contact layer 110 to form a beam outward thepoint source LED.

Because of the local current is concentrated in the light emitting areaL. Therefore, the brightness and the beam-coupling ratio of the pointsource LED are enhanced, and by effectively concentrating the localcurrent, a predetermined light beam can be provided, and the opticalfiber can be coupled directly without any additional optical splitdevice.

Referring to FIG. 2 a to FIG. 2 h, FIG. 2 a to FIG. 2 h are a series ofcross section diagrams showing the process steps of the point source LEDin accordance with the second embodiment of the present invention.

Referring to FIG. 2 a, an epitaxy structure 202 comprising a bufferlayer 201, an n-type cladding layer 203, an active layer 205, and aP-type cladding layer 207 is formed on a substrate 200 by a metalorganic chemical vapor deposition (MOCVD) process. The epitaxy structure202 is made of III–V semiconductor materials, such as GaP,Ga_(1-x)Al_(x)As, GaAs_(1-y)P_(y), ZnS_(1-z)Se_(z), AlGaInP, AlInGaN,wherein MgZnSSe, AlGaInP, AlInGaN, MgZnSSe, and Ga_(1-x)Al_(x)As arepreferable. In the embodiment, the preferred material of buffer layer201 may be such as n-type GaAs. The n-type cladding layer 203 may bepreferably made of a wide bandgap n-type AlGaInP. The active layer 205may be preferably made of narrow bandgap AlGaInP, or AlGaInP withmulti-quantum well. The preferable material of p-type cladding layer 207may be wide bandgap p-type AlGaInP.

Next, referring to FIG. 2 b, FIG. 2 b is the cross sectional viewshowing the structure after a first electrode 204 is formed on theepitaxy structure 202. The materials of excellent conductivity with theepitaxy structure 202 can be deposited on the epitaxy structure 202 by adeposition process, for example, electron enhanced evaporation, thermalevaporation, or sputtering deposition, to form the first electrode 204.The materials used to form the first electrode 204 comprise an ohmicmetal layer or a transparent conductive material, wherein thetransparent conductive material can be such as ITO, ZnO, SnCdO, WTiN,InO, SnO, MgO. The ohmic metal layer can be such as Au, Ag, Al, Ni, Ti,Cr, Au alloy, or other metal. In the second embodiment of the presentinvention, the first electrode 204 is made of Au alloy.

Referring to FIG. 2 b, FIG. 2 b is the cross sectional view showing thestructure after the first electrode 204 of the FIG. 2 is patterned.After the first electrode 204 is formed, a first photoresist (not shown)is deposited on the first electrode 204, and then the first electrode204 is etched, so that one portion of the epitaxy structure 202 can beexposed. As a result, a structure of the FIG. 2 b is formed after thefirst photoresist is removed.

Referring to FIG. 2 c, FIG. 2 c is the cross sectional view showing thestructure after an isolation layer 208 is formed on the structure of theFIG. 2 b. An isolation material, such as SiON, SiNx, SiO₂, AlO₂ orpolyimide is deposited on the first electrode 204 and the exposedportion of the epitaxy structure 202. Then, portions of the isolationmaterial above the top surface of the first electrode 204 are removed toform the isolation layer 208.

Referring to FIG. 2 d, FIG. 2 d is the cross sectional view showing thestructure after a metal layer 213 is formed on the structure of the FIG.2 c. A deposition process, such as electron enhanced evaporation,thermal evaporation, or sputtering deposition, is conducted to form themetal layer 213 on the first electrode 204 and the isolation layer 208.The materials used to make of the metal layer 213 can be such as Au, Ag,Al, Ni, Ti, Cr, Au alloy, or other metal. In the second embodiment ofthe present invention, the metal layer 213 is made of Au alloy.

After the metal layer 213 is formed, a pattern process is conducted.Referring to FIG. 2 e, FIG. 2 e is the cross sectional view showing thestructure after the pattern process is conducted on the metal layer 213.A second photoresist (not shown) is formed on the metal layer 213.Before the second photoresit is removed, an etching process is performedon the metal layer 213 to expose portions of the isolation layer 208 andportions of the epitaxy structure 202. The remaining metal layer 213comprises three parts including a bonding layer 212 a, a contact layer210 a, and a connection bridge 214 a. The contact layer 210 a and theconnection bridge 214 a are located on and adjacent to the isolationlayer 208 but do not contact the epitaxy structure 202 directly. Thecontact layer 210 a is located on the first electrode 204, and forms anelectric contact between the contact layer 210 a and the first electrode204. In the second embodiment of the present invention, the contactlayer 210 a is in alignment with the first electrode 204, and thecontact layer 210 a and the bonding layer 212 a are electricallyconnected by the connection bridge 214 a and 214 b. The connectionbridge 214 a is a narrow electrically conductive passage having a width,and the width is less than one half of the diameter of the contact layer210 a. The contact layer 210 a can be in various shapes, such as acircle, a ring, a polygon, or a cross. The bonding layer 212 a is atarget area for the subsequently bonding process to connect outer wires(not shown).

Next, a mesa etching process is conducted to the epitaxy structure 202adjacent to the first electrode 204 and the isolation layer 208.Referring to FIG. 2 f, FIG. 2 f is the cross sectional structure afterthe epitaxy structure 202 of FIG. 2 e is mesa etched. A mask (not shown)is formed to cover the patterned metal layer 213 and one portion of theisolation layer 208. Before the mask is removed, an etching process,such as wet etching or reactive ion etching, is performed at least toform a light emitting area L in the epitaxy structure 202 beneath thefist electrode 204. The light emitting area L can be in various shapes,such as a circle, a ring, a polygon, or a cross. In the secondembodiment of the present invention, the light emitting area L is acircle with a diameter less than 150 μm.

Consequently, a second electrode 206 is formed on one side of thesubstrate 200. Referring to FIG. 2 g, FIG. 2 g is the cross sectionalstructure after a second electrode 206 is formed on the structure ofFIG. 2 f. In the embodiment of the present invention, the secondelectrode 206 is deposited on the substrate 200. In the otherembodiments of the present invention, the second electrode 206 also canbe formed on the part of the surface of the epitaxy structure 202 thatis not etched by the mesa etching process (referring to FIG. 1 a).Before the second electrode 206 is deposited on the substrate 200, aprotection layer (not shown) is formed on the exposed part of the n-typecladding layer 203, the metal layer 213, portion of isolation layer 208,and the sidewalls of these layers, so as to prevent the second electrode206 from making direct electric contact with the metal layer 213, thefirst electrode 204, and the mesa etched surface of the epitaxystructure 202. The preferable materials of the protection layer can beSiO₂ or SiO.

According to the invention, the first electrode 204 and the secondelectrode 206 are formed on the epitaxy structure 202, and the firstelectrode 204 cannot contact the second electrode 206 directly. In someembodiments of the present invention, the first electrode 204 and thesecond electrode 206 are located on the same side of the substrate 200(such as shown in FIG. 1 a). In the other embodiments of the presentinvention, the first electrode 204 and the second electrode 206 arelocated on the opposite sides of the substrate 200 respectively (such asshown in FIG. 1 c). In the second embodiment of the present invention,the first electrode 204 and the second electrode 206 are located on theopposite sides of the substrate 200 respectively.

The materials used to form the second electrode 206 can be thematerials, such as ohmic metal or transparent electrode, wherein thetransparent electrode can be such as ITO (indium-tin-oxide), ZnO, SnCdO,WtiO, InO, SnO or MgO. The ohmic metal can be such as Au, Ag, Al, Ni,Ti, Au alloy, or other metal. In the first embodiment of the presentinvention, the second electrode 206 is made of Au alloy.

Then, the protection layer is removed. Referring to FIG. 2 h, FIG. 2 his the cross sectional view showing the structure after a patternedpassive layer 216 is formed on the structure of FIG. A passive layer 216is deposited on the exposed part of the n-type cladding layer 203, themetal layer 213, the first electrode 204, and the isolation layer 208.Then, a pattern process is performed on the passive layer 216 to producea pattern that can expose one portion of the bonding layer 212 a. Theexposed part of the bonding layer 212 a named bonding area B can providea location for a bonding processes. The preferred material for formingthe passive layer 216 can be such as polyimide, polymer, SiNx, SiNxOy orSiO₂.

Local current, flowing from the outer wires through the bonding area B,the connection bridge 214 a, the contact layer 210 a, and the firstelectrode 204, can be conducted into the epitaxy structure 202. Becauseof the use of the designed patterns formed on the first electrode 204,and the contact layer 206, the local current form the outer conductivewire can be concentrated in the light emitting area L below the firstelectrode 204 before the local current flowing into the active layer205. Light emitted from the active layer 205 can go through the lightemitting area L, the first electrode 204, and the contact layer 210 a toform a beam outward the point source LED.

According to the aforementioned description, one advantage of thepresent invention is that the use of designed patterns of the firstelectrode 204, the contact layer 206, and the mesa etched epitaxystructure 202 to produce a light beam with high brightness, and highbeam-coupling ratio. The designed patterns can concentrate the emittedlight and can eliminate the affect of the bonding wire to provide theemitted light beam a predetermined shape.

According to the aforementioned description, with the application of thepoint source LED of the present invention, the problems of low coupleratio of LED can be resolved without adding any complex steps.

As is understood by a person skilled in the art, the foregoing preferredembodiments of the present invention are illustrated of the presentinvention rather than limiting of the present invention. It is intendedto cover various modifications and similar arrangements included withinthe spirit and scope of the appended claims, the scope of which shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar structure.

1. A point source light emitting-diode (LED), comprising: a substrate;an epitaxy structure located on the substrate, the epitaxy structurehaving a pattern, wherein the pattern is located on a light emittingsurface of the epitaxy structure, and includes a light-emitting area; afirst electrode located on one portion of the epitaxy structure; anisolation layer located on the other portion of the epitaxy structure,wherein the isolation layer is adjacent to the first electrode; acontact layer located on the first electrode; a bonding layer located onone portion of the isolation layer; and a connection bridge located onthe other portion of the isolation layer, wherein the connection bridgeis used to connect the contact layer to the bonding layer, and theconnection layer has a width, and the width is less than one half of thediameter of the light emitting area.
 2. The point source LED accordingto claim 1, further comprising: a passive layer located above thecontact layer, the connection bridge, the bonding layer, the isolationlayer, and the epitaxy structure.
 3. The point source LED according toclaim 2, wherein passive layer is made of an isolation material, and theisolation material is selected from the group consisting of polyimide ,polymer, SiNx, SiO₂, and the combination thereof.
 4. The point sourceLED according to claim 2, wherein the passive layer comprises a bondingarea pattern exposing one portion of the bonding layer used forpositioning purpose in a bonding process.
 5. The point source LEDaccording to claim 1, wherein the light emitting area is located belowthe first electrode, and the light emitting from the active layer can gothrough the light emitting area, the first electrode, and the contactlayer.
 6. The point source LED according to claim 1, wherein the shapeof the light emitting area is selected from a group consisting of acircle, a ring, a polygon, and a cross.
 7. The point source LEDaccording to claim 1, wherein the light emitting area having a diameterless than 150 μm.
 8. The point source LED according to claim 1, whereinthe first electrode is made of a transparent conductive materialselected from a group consisting of ITO (Indium-Tin-Oxide), ZnO, SnCdO,WTiN, InO, SnO, and MgO.
 9. The point source LED according to claim 1,wherein the electrode is made of an ohmic metal selected from a groupconsisting of Au, Ag, Al, Ni, Ti, and Au alloy.
 10. The point source LEDaccording to claim 1, wherein the contact layer is a patternedconductive layer, wherein the shape of the patterned conductive layer isselected from a group consisting of a circle, a ring, a polygon, and across.
 11. The point source LED according to claim 10, wherein thecontact layer is made of an ohmic metal selected from a group consistingof Au, Ag, Al, Ni, Ti, and Au alloy.
 12. The point source LED accordingto claim 1, wherein the contact layer, the bonding layer, and theconnection bridge are formed simultaneously as a single layer with thesame materials by the same processes.
 13. The point source LED accordingto claim 1, wherein the contact layer, the bonding layer, and theconnection bridge are multiple layers made of different materials bydifferent processes respectively.
 14. The point source LED according toclaim 1, wherein the connection bridge having a width less than 30 μm.15. The point source LED according to claim 1, wherein the isolationlayer is located between the bonding layer and the epitaxy structure.16. The point source LED according to claim 1, wherein the isolationlayer is selected from a group consisting of SiON, SiO₂, AlO₂, polyimid,and the combination thereof.
 17. The point source LED according to claim1, further comprising a second electrode located on one side of thesubstrate.
 18. The point source LED according to claim 17, wherein thesecond electrode and the first electrode are located on the same side ofthe substrate.
 19. The point source LED according to claim 17, whereinthe second electrode and the first electrode are located on the oppositesides of the substrate respectively.
 20. The point source LED accordingto claim 17, wherein the epitaxy structure is made of III–Vsemiconductor materials, having a structure including a buffer layer, ann-type cladding layer, an active layer, and a P-type cladding layerstacked sequentially.
 21. A surface structure of a point source LED,comprising: an patterned epitaxy structure having a light emitting area;an electrode located on one portion of the patterned epitaxy structure;an isolation layer located on the other portion of the patterned epitaxystructure adjacent to the electrode, wherein the isolation layer isconnected with the electrode, and a light emitting area can be definedby the combination of the isolation layer and the electrode; a contactlayer located on one portion of the electrode; a bonding layer locatedon one portion of the isolation layer; a connection bridge located onthe other portion of the isolation layer, wherein the connection bridgeis used to connect the contact layer to the bonding layer, and theconnection layer has a width, and the width is less than one half of thediameter of the light emitting area; and a passive layer exposing oneportion of the bonding layer to provide a location for a bondingprocess.
 22. The surface structure of a point source LED according toclaim 21, wherein the surface structure of a point source LED is coupledwith an optical fiber directly.